Field
Embodiments described herein generally relate to a clamp ring for use in a chemical mechanical polishing carrier head, wherein the clamp ring includes an outer cylindrical wall configured to prevent adherence and agglomeration of slurry particles to the clamp ring.
Description of Related Art
Integrated circuits are typically formed on substrates, such as silicon wafers, by sequential deposition of conductive, semiconductive, or insulative layers. After each layer is deposited, the layer is etched to create circuitry features. As a series of layers are sequentially deposited and etched, the outer or uppermost surface of the substrate, i.e., the exposed surface of the substrate, becomes increasingly non-planar. This non-planar outer surface presents a problem for the integrated circuit manufacturer. Therefore, there is a need to periodically planarize the substrate surface to provide a flat surface.
Chemical mechanical polishing (CMP) is one accepted method of planarization. CMP typically requires that the substrate be held by a carrier head in a manner that leaves a device side surface of the substrate exposed. The carrier head positions the substrate against a rotating polishing pad. The carrier head provides a controllable load, i.e., pressure, on the substrate to push the substrate against the rotating polishing pad. In addition, the carrier head may rotate to provide additional motion between the substrate and polishing surface.
A polishing slurry, including an abrasive and at least one chemically-reactive agent, may be supplied to the polishing pad to provide an abrasive chemical solution at the interface between the pad and the substrate. The polishing slurry may also contact and adhere to surfaces of the carrier head. Over time, the abrasives within the polishing slurry begin to agglomerate on the surfaces of the carrier head. The agglomerated slurry particles may dislodge from the surfaces of the carrier head, and fall onto the pad while polishing the substrate, which may result in scratching of the substrate. Scratches may result in substrate defects, which lead to performance degradation while polishing of the finished device. The agglomerated slurry particles are particularly problematic on surface with the carrier head that cannot be effectively rinsed between the polishing of substrates.
Therefore, there is a need to improve components of a carrier head to reduce the potential of polishing slurry to adhere to the carrier head.